Z. G. Tari, L. Wang and B. Sundén Division of Heat Transfer, Department of Energy Sciences, Faculty of Engineering (LTH), Lund University (B. Sundén ) Industrial Research Managers H. Abrahamsson, A. Borg, L. Ström Volvo Aero Corporation, S , Trollhättan, Sweden Internal Cooling of Hot Turbine Structures

Part (1) TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU 2/16 Agenda  Introduction  Turbine structures  Test rig  Thermal section  Thermal measurement procedure by liquid crystal thermography (LCT)  Challenges in thermal measurements  Selected results  Present status - next step  Publications

Turbofan (GP7000) engine Turbine section 1.Fan section 2.Compressor section 3.Combustion section TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Background - Turbine structures ”cold” strut bearing ”hot”vane shaft HPT IPT LPT - Two part structure:  Hot vanes  Cold load carrying structure Front turbine structures - Most engines have a structure betweeen HPT and LPT 3/16

Flows of interest is a combination of: - Channel flow with  Curvature  Injection (feed jet, slots)  Wall disturbances, e.g., ribs  Blockage  Leakage - Cavities without pre-dominant flow direction, governed by jet and leakage flows - creating a chaotic, low velocity highly turbulent flow. Inner support TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Flows connected to cooling 4/16

Part (1) Test rig Test section, flexible walls Air intakeSuction fan Downstream towards fan Upstream of fan TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Thermal section 5/16

Part (1) Measuring principles-LCT examples  The test surface temperature is maintained within the linear portion of the calibration curve by controlling the heat flux.  Repeating the tests at the same flow rate and for different values of the heat flux to cover the whole surface. q1 h [W/m 2 K] 2-D plot heat transfer coefficient (W/m 2 K) for a given configuration at Re = 8900 [2] TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU q2q3 << 6/16

TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Challenges - thermal measurements Selected results  Ensure sufficient time to attain steady state  Improve the accuracy in heat flux measurements  Avoid non-linear hue range  Reduce the non-uniformity of heat flux Symptom of a non-uniform heat flux- electric tracks Distribution of HT for the ribbed duct, Re = 48,000 (p/e= 10) Hue = (linear range) rib Distribution of HT for the ribbed duct, Re = 48,000 (p/e= 10) Hue = (including non-linear portion) rib 7/16 Hue- temperature calibration for wide-band LCT green blue red

Part (1) Heating Steady state-constant heat flux Challenges  Applied heating foil must provide uniform heat flux through the test section.  Metal plate helps to create uniform heating Thermal contact resistance and associated temperature drop occurs when different conducting surfaces, e.g., heating foil, metallic foil, LCT do not fit together tightly. Symptom of a non-uniform heat flux; electric tracks are clearly visible More uniform heat flux distribution; a thin stainless steel foil between LC and heating foil Symptom of a non-uniform heat flux TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU 8/16

Part (1) Thermal test section - improved TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU LCT Stainless steel Heating foil Plexiglas insulation Composite structure of thermal section wall (improved arrangement) 9/16 LCT Heating foil Plexiglas insulation Composite structure of thermal section wall (old arrangement) y z 320 mm 500 mm LCT CCD camera 80 mm x

Part (1) Selected results ( Smooth duct) TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Asymmetric heating correlation, R. Matsumoto et al. [1997] : Nu = Re D 0.8. Pr / mm flow 320 mm Smooth configuration-top views

Part (1) Selected results (Rib measurements) Rib arrangements - top views: TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU W (mm) H (mm) l (mm) e (mm)p/ee/D h flow p/e = mm 320 mm 500 mm flow p/e = mm l 11/16

TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU 12/16 Selected results – Diploma work (Volvo Aero) (Ribbed duct, p/e = 10)

TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU 13/16 Selected results (Inclined impinging jet) 2D plot of local Nusselt number for an inclined impinging jet in cross flow. Re duct = , Re jet = Visualization of inclined impinging jet – strip heating

Part (1) TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU  Diploma work – Volvo Aero (finalized June 2011)  Present status - Calibration LCT – color play band of 5 ºC  Thermal measurements - Investigation with ribs having large rib spacings p/e = 10, 20, 30 Re D = 48, ,000 - Presentation 15th CMEM - Delivery: IMECE2011 (in preparation) - Licentiate Thesis 14/16 Summary

Part (1) TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU Publications 1. Z. Ghorbani -Tari, L. Wang, B. Sunden, Heat transfer measurements in rectangular duct using hue-based calibrated wide –band thermochromic liquid crystal, CD Proceedings ASME - ATI-UIT 2010 Conference on Thermal and Environmental Issues in Energy Systems, Vol. II, paper HT029, , Z. Ghorbani -Tari, B. Sunden, G. Tanda, On liquid crystal thermography for determination of heat transfer coefficients in Rectangular ducts, CMEM2011, 15 th Int. Conf. Computational Methods and Experimental Measurements, UK, Z. Ghorbani –Tari, Experimental Investigation of Convective Heat Transfer in a Rectangular Duct with a limited Number of Transverse Ribs by Liquid Crystal Thermography, Licentiate of Engineering Thesis, to appear spring L. Wang, M. Salewski, B. Sunden, Turbulent flow in a ribbed channel: flow structures in the vicinity of a rib, Experimental Thermal and Fluid Science, Vol. 34, no. 2, , L. Wang, M. Salewski, B. Sunden, Turbulent flow in a ribbed channel analyzed by the proper orthogonal decomposition, ExHFT-7,(CD-ROM Proceedings), , L. Wang, M. Salewski, B. Sunden, Unsteady turbulent flow in a channel with periodic transverse ribs on one wall, ICHMT symposium on Turbulent Heat and Mass Transfer, Rome, Italy (CD-ROM Proceedings). 7. B. Sunden, On heat transfer and fluid flow in ribbed ducts using liquid crystal thermography and PIV measurements, EXHTF- 7 (CD-ROM Proceedings), , L. Wang, B. Sunden, A. Borg, H. Abrahamsson, Effects of shallow-angle jet impingement and free stream velocity on heat transfer, IMECE , L. Wang, B. Sunden, A. Borg, H. Abrahamsson, Heat Transfer Characteristics of an Impinging Jet in Crossflow, ASME J. Heat Transfer ( in revision phase), L. Wang, B. Sunden, A. Borg, H. Abrahamsson, Endwall heat transfer of flow past bluff body, (report in progress for Journal publication), L. Wang, B. Sunden, A. Borg, H. Abrahamsson, Heat transfer in a channel under effects of a shallow-angle jet impingement and a rib, GT , /16

Part (1) TURBO POWER - CHALMERS 2011/ Zahra G.Tari - LU